Rational design of n-Bi12TiO20@p-BiOI core–shell heterojunction for boosting photocatalytic NO removal

Bismuth titanate (Bi 12 TiO 20 ) with unique sillenite structure has been shown to be an excellent photocatalyst for environmental remediation. However, the narrow light-responsive range and rapid recombination of photoinduced electrons-holes limit the photocatalytic performance of Bi 12 TiO 20 . To overcome the limitations, a practical and feasible   way is to fabricate heterojunctions by combining Bi 12 TiO 20 with suitable photocatalysts. Here, using a facile chemical precipitation method, a novel and hierarchical core–shell structure of n-Bi 12 TiO 20 @p-BiOI (BTO@BiOI) heterojunction was rationally designed and synthesized by loading BiOI nanosheets on BTO nanofibers. The constructed BTO@BiOI composites exhibited significant charge transfer ability due to the synergistic effects of the built-in electric field between BTO and BiOI as well as close interfacial contacts. In addition, the narrow bandgap   characteristics of the BiOI led to wide light absorption ranges. Therefore, the BTO@BiOI heterojunction exhibited an improved photocatalytic performance under visible light irradiation. The NO removal efficiency of optimal BTO@BiOI was 45.7%, which was significantly higher compared to   that of pure BTO (3.6%) or BiOI (23.1%). Moreover, the cycling experiment revealed that BTO@BiOI composite has a good stability and reusability. The possible mechanism of photocatalytic NO oxidation over BTO@BiOI was investigated in detail.